docs: reconciliar OpenSpec e escopo do MVP (MAN-124) (#50)

openspec/changes/archive/2026-08-11-enhance-public-motion/specs/public-site-motion/spec.md

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+## ADDED Requirements
+
+### Requirement: Public pages use shared progressive motion choreography
+
+The public site SHALL expose a declarative motion contract using `data-motion="page-open"`, `data-motion-beat`, `data-reveal-group`, `data-reveal`, and `data-reveal-from="up|left|right"`. Home, services, portfolio index/detail, about, contact, privacy, and branded 404/419/429/500/503 pages MUST use the contract without introducing route transitions.
+
+#### Scenario: Visual public route exposes motion hooks
+- **WHEN** a visitor loads any visual public route or branded error page
+- **THEN** the rendered page MUST expose a page opening hook and appropriate reveal hooks
+
+#### Scenario: Technical endpoints remain outside motion
+- **WHEN** a visitor requests `sitemap.xml` or `robots.txt`
+- **THEN** the response MUST NOT depend on the public motion runtime
+
+### Requirement: Editorial entrance timing and direction are consistent
+
+Entrances SHALL use shared tokens for an approximately 500 ms duration, 90 ms stagger capped at 270 ms, 12 px vertical distance, and 24 px desktop / 16 px mobile lateral distance. Text MUST remain fully visible; motion MUST use transforms and MAY use media clipping without opacity fades for text.
+
+#### Scenario: Reveal group computes capped stagger
+- **WHEN** more than four reveal items are rendered in one group
+- **THEN** the applied delay MUST NOT exceed 270 ms
+
+#### Scenario: Text enters without opacity fade
+- **WHEN** page opening or scroll reveal motion runs
+- **THEN** text MUST remain visible throughout the transition
+
+### Requirement: Reveals execute once without blocking interaction
+
+Each scroll reveal SHALL activate once, reach its final state, and be removed from observation. Visitors MUST be able to activate links and form controls while entrance motion is running.
+
+#### Scenario: Revealed content leaves observer
+- **WHEN** a reveal target intersects the configured viewport threshold
+- **THEN** it MUST receive the final state and be unobserved
+- **AND** scrolling away and back MUST NOT replay the reveal
+
+#### Scenario: CTA remains interactive during entrance
+- **WHEN** a visitor activates a CTA while its entrance is in progress
+- **THEN** navigation MUST proceed without waiting for animation completion
+
+### Requirement: Motion enhancement has immediate safe fallbacks
+
+Without JavaScript, without `IntersectionObserver`, or when `prefers-reduced-motion: reduce` is active, the site SHALL render every motion target immediately in its final usable state. Non-essential animation and transition MUST NOT run under reduced motion.
+
+#### Scenario: JavaScript is unavailable
+- **WHEN** a public page renders without executing JavaScript
+- **THEN** all content MUST be visible and usable in its final state
+
+#### Scenario: IntersectionObserver is unavailable
+- **WHEN** JavaScript runs but `IntersectionObserver` is not supported
+- **THEN** all reveal targets MUST remain in their final state
+
+#### Scenario: Reduced motion is preferred
+- **WHEN** the browser reports `prefers-reduced-motion: reduce`
+- **THEN** page openings, reveals, media clips, and non-essential feedback transitions MUST NOT run
+
+### Requirement: Public interaction feedback is short and accessible
+
+CTAs, links, navigation, and form controls SHALL provide short feedback using shared tokens while preserving visible `:focus-visible` indication. Alerts and validation messages MUST NOT be animated by this contract.
+
+#### Scenario: Keyboard focus remains visible
+- **WHEN** a visitor focuses an interactive element with the keyboard
+- **THEN** its focus indicator MUST remain visible and MUST NOT be displaced by motion feedback
+
+#### Scenario: Validation message appears without motion
+- **WHEN** server validation renders an error message
+- **THEN** the message MUST appear in its final position without entrance animation
+
+### Requirement: Home progress updates at most once per animation frame
+
+Scroll-driven chapter index and progress updates on the home SHALL be coalesced through `requestAnimationFrame`, with at most one pending update per frame.
+
+#### Scenario: Multiple scroll events occur in one frame
+- **WHEN** multiple scroll events fire before the next animation frame
+- **THEN** the home progress calculation MUST execute only once for that frame